To test a newly formulated protein bar designed to improve running performance, 10 distance runners performed two trials.All the participants ate the new protein formula bar on the first trial. In the second trial, the same participants ate the regular (old) protein bar. Thirty minutes after consuming the bar the participant ran for 2 hours on a treadmill.

At the end of the two trials, performed on consecutive days for each participant, the distance each participant ran (in km) was recorded. The data is below.

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